Wongnen et al., 2009. Asian-Aust. J. Anim. Sci., 22 (12): 1625-1632

Four lactating Holstein Friesian crossbred cows, with an average initial weight of 450 kg, 48±12 days in milk and initial milk yield of 18 kg/h/d, were randomly arranged according to a 2x2 factorial arrangement in a 4x4 in Latin square design with 21-d period to investigate the effects of type of total mixed ration (TMR) and type of whole cottonseed (WCS) on intake, digestibility and milk production. The dietary treatments were i) TMR and WCS supplementation at 0.5 kg/h/d, ii) TMR and cracked WCS (cWCS) supplementation at 0.5 kg/h/d, iii) fermented TMR (FTMR) and WCS supplementation at 0.5 kg/h/d, and iv) FTMR and cWCS supplementation at 0.5 kg/h/d. Voluntary feed intake was 15.9, 15.2, 15.4 and 15.6 kg DM/d in dietary treatment 1, 2, 3 and 4, respectively. Digestibility of DM, OM, CP, EE, NDF and ADF were not significantly different among dietary treatments. Ruminal pH, NH3-N and volatile fatty acids in the rumen were also not significantly different among type of TMR or type of WCS. Blood urea-N concentration was not significantly different among dietary treatments. Ruminal bacteria population tended to increase but ruminal protozoa population tended to decrease with supplementation of cWCS, but they were not affected by FTMR. Milk yield and 3.5% FCM were not statistically different among treatments (16.6, 16.2, 17.0, 16.3 kg/d and 18.0, 18.6, 19.9 and 19.0 kg/d, respectively). Milk composition was not significantly different among dietary treatments. However, unsaturated fatty acids in milk fat in cows fed FTMR were lower (p<0.05) than in cows fed TMR. In conclusion, fermentation is a conceivable method to improve the quality of TMR for long-time storage and the cracking method is suitable to release the fat from cottonseed for enhancing fatty acid deposition in milk. Thus, the combination of FTMR and cWCS supplementation would be an alternative strategy to improve performance of lactating cows.